JP2002179973A - Water-soluble burned colored lead and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-soluble burned lead which has excellent color developability, density of depicted lines, and light-resistance and is suited in use for high flexural strength mechanical pencils having water-soluble depicted lines, and its manufacturing method. SOLUTION: The lead comprises a pigment to be represented by formula (I) A(B)x (x is an integer of 1-8; A is a residue of a chromophore such as quinacridone and anthraquinone and is bonded to B by one or more atoms of N, O, and S in A; B is H or-COOL and at least one of B is a group excluding H; and L is a group which expresses solubility) and at least one kind of the compounds to be represented by formulae (II) to (IV) (R is a 10-20C alkyl group or an alkenyl group; and n is an integer of not smaller than 20) in the pores of a white or hypochromic porous burned lead body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a vivid color development,
While having a sufficient drawing line density, it is possible to draw lines with excellent light resistance, the drawing lines are easily dissolved with water, and it has excellent mechanical strength such as bending strength, and it is also used for sharp pencils, small diameter pencils for holders The present invention relates to a suitable water-soluble fired color pencil lead and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a fired pencil lead is often used for a mechanical pencil, and is manufactured by kneading and extrusion-molding a compounded composition comprising a material such as boron nitride and a binder such as clay. The main method is to form a porous core after further heat treatment, and to fill the pores of the core with an ink comprising a dye, a solvent or the like.

If an aqueous ink or an ink compatible with water is used as the dye ink, it can be used as a water-soluble colored pencil lead, but the solubility in water is insufficient, and the colorant is a dye. , Etc. over time. Further, if a core having pores of a size that can be impregnated with the pigment-dispersed ink is used, the core has low strength and is not practically used as a core for a mechanical pencil.

As a method for obtaining a high-strength core, for example,
JP-A-8-48931, JP-A-9-67540, JP-A-2000-17220, JP-A-20
No. 00-17221 is disclosed, but any method can impregnate a sufficient amount of the pigment-dispersed ink as the drawing line density, and obtain a fired core having a strength not lower than a practical level as a mechanical pencil lead. It is difficult.
Accordingly, the present inventors have proposed a method for producing an organic pigment in a pore of a porous core material for a mechanical pencil by a chemical reaction or the like, for example, JP-A-8-143810, JP-A-8-143911, JP-A-8-143812, JP-A-8-259874, Japanese Patent Application No. 11-1
No. 49188 has been filed. These are ordinary color pencils for mechanical pencils in which the drawing lines do not dissolve in water.

[0005] The water-soluble color pencil lead of a normal wooden shaft is a part of the wax of a non-baked color pencil lead that is not dissolved in ordinary water and is composed of a composition such as a pigment, a body material, a paste and a wax.
Alternatively, it is manufactured with a composition in which all of the ingredients are replaced with a waxy surfactant or the like. This core does not pose a problem in the state where it is placed in a wooden shaft, because the wooden shaft suppresses moisture absorption.However, when used for a mechanical pencil, the original strength is weak, but it is due to the absorption of waxy surfactant and paste material. The strength is remarkably reduced and is not practical.

On the other hand, as a water-soluble colored pencil lead, for example,
JP-A-62-121778, JP-A-63-199
775, JP-A-3-153778, JP-A-3-153779, JP-A-4-209676, JP-A-5-230414, JP-A-8-600
No. 66, JP-A-9-67542, JP-A-9-67542
No. 202869 and the like are disclosed.
Since each of them is the same production method as the above-mentioned water-soluble non-baked color pencil lead, the strength is originally low, and the strength is significantly reduced due to moisture absorption, so that it cannot be used for mechanical pencils and holders.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the above-mentioned prior art water-soluble non-fired color pencil lead and conventional fired color pencil lead (water-insoluble). Water-soluble sintering that dissolves to give a watercolor-like drawing, has vivid color development, has a sufficient drawing line density, can write lines with excellent light and weather resistance, and has excellent mechanical strength such as bending strength. An object is to provide a colored pencil lead and a method for producing the same.

[0008]

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned conventional problems. As a result, a specific compound is filled in the pores of a white or light-colored porous fired core. It was found that the above-mentioned water-soluble calcined colored pencil lead and the method for producing the same can be obtained by heating to form a pigment, and further filling at least one of the specific compounds in the remaining portions of the pores. It was completed. That is, the present invention resides in the following (1) to (4). (1) A pigment starting from at least a compound represented by the following general formula (I) and a compound represented by the following general formulas (II) to (IV) in pores of a white or light-colored porous fired core. A water-soluble calcined colored pencil lead, characterized by containing at least one of the following.

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Embedded image (2) The aqueous solution according to the above (1), wherein the white or light-colored porous fired core comprises a colorless or white body material and silicon nitride starting from perhydropolysilazane as a binder. Colored pencil lead. (3) A white or light-colored porous fired core is formed, and at least a compound represented by the following formula (I) is dissolved in an organic solvent and filled in pores of the fired core, and then heated to form a porous body. A water-soluble calcined colored pencil characterized in that a compound is formed into pigments in the pores, and the remaining portion of the pores is filled with at least one compound represented by the following general formulas (II) to (IV): Manufacturing method of core.

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Embedded image (4) The white or light-colored porous calcined core comprises a colorless or white body material, and a silicon nitride starting from perhydropolysilazane as a binder as described in (3) above, A method for producing a water-soluble calcined colored pencil lead.

[0009]

Embodiments of the present invention will be described below in detail. The water-soluble calcined colored pencil lead of the present invention comprises an organic pigment formed after filling a compound represented by the following general formula (I) into pores of a white or pale-colored porous calcined core and heating, and an organic pigment represented by the following general formula (II) ) To (IV).

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In the production of the water-soluble calcined colored pencil lead of the present invention, a white or pale colored porous calcined core is formed, and at least the compound represented by the above general formula (I) is added to the pores of the calcined core. After dissolving and filling in a solvent, the compound is heated to form a pigment in the pores, and at least one of the compounds represented by the above general formulas (II) to (IV) is added to the remaining portion of the pores. Is carried out.

In the present invention, the porous fired core body is a conventionally known one. At least a colorless or white body material such as boron nitride, talc, mica and the like, and silicon nitride, silica, alumina, zirconia and It is formed from these solid solutions or clay and the like. In particular,
From the viewpoint of strength, a core using perhydropolysilazane as a starting material and using silicon nitride as a binder as disclosed in Japanese Patent Application Laid-Open No. 8-48931 by the present applicant is preferable.

The body material is conventionally used as a body material for a fired color pencil lead, and is not particularly limited as long as it is colorless or white, and any of them can be used. Various types of materials can be used, and of course, these can be used alone or as a mixture of two or more types. Further, depending on the type of the binder, the firing temperature, and the like, silica and alumina can also be used as the body material.

The open pore diameter of the porous colored pencil lead used in the present invention is not particularly limited as long as it can be impregnated with a solution obtained by dissolving the above general formula (I) in an organic solvent. However, the minimum value of the open pore diameter is approximately 0.05
Since it is considered to be μm, it is desirable to use those having open pores of 0.05 μm or more, but when considering the distribution of open pores, a large amount of open pores are distributed in a range smaller than 0.05 μm. In this case, the number of pores not filled with pigment increases and the color developability deteriorates. Therefore, the open pores smaller than 0.05 μm have a volume of 40% or less, more preferably 20% or less.
%. The maximum value of the open pore diameter is preferably 0.4 μm or less in consideration of the core strength and the like. Also,
Considering the coloring property on the paper surface and the water solubility of the drawing line,
The open porosity of the porous pencil lead distributed in the range of 0.05 μm or more and 0.4 μm or less, more preferably 0.3 μm or less, is 15% or more, more preferably 20% or more. Is desirable.

In the present invention, the water-soluble calcined colored pencil lead is prepared by dissolving the compound represented by the above formula (I) in an organic solvent, impregnating and filling the pores of the porous calcined lead, and then heating. To produce an organic pigment, and the remaining portions of the pores are filled with at least one of the compounds represented by the general formulas (II) to (IV).
The compound represented by the above general formula (I) used in the present invention is
It is a compound that serves as a pigment precursor, and is formed into an organic pigment by filling the pores of the porous fired core with the compound and heating. In the above general formula (I), x is 1 to 8
Wherein the group A comprises a chromophore residue of quinacridone, anthraquinone, perylene, indigo, quinophthalone, indathrone, isoindolinone, isoindoline, dioxazine, azo series, phthalocyanine or diketopyrrolopyrrole. And these groups A
Is bonded to x groups B via one or more heteroatoms among a nitrogen atom (N), an oxygen atom (O) or a sulfur atom (S) among the heteroatoms which are part of Things. This group B is a hydrogen atom (H) or -CO
A group represented by OL, at least one of the groups B is a group other than a hydrogen atom (H), and when x is 2 to 8, all the groups B are the same, or It may be different. Furthermore, the above L is a group that expresses solubility, and is not limited to the above as long as it is a group that expresses solubility, and examples thereof include tert-butyl and tert-amyl. In the present invention, the organic solvent for dissolving the compound represented by the general formula (I) may be any organic solvent that can dissolve the compound represented by the general formula (I).
The invention is not limited thereto, and for example, any of aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, amides, nitriles, nitro compounds, N-heterocyclic compounds, ethers, ketones, esters and the like can be used. Although it is possible, and in some cases, water can be used, the boiling point of these solvents is preferably from 40 ° C to 300 ° C. Further, regarding the solubility, a solvent capable of dissolving the compound represented by the formula (I) in an amount of 5% by weight or more, preferably 10% by weight or more in terms of the concentration of the drawn line of the core is desirable. Specific examples include methanol, ethanol, isopropanol, n-butanol, benzyl alcohol, diethyl ether, 1-acetoxy-2-ethoxyethane, acetone, methyl ethyl ketone, cyclopentanone, butyrolactone, 1-methoxy-2-propanol, , 2-dimethoxyethane,
1,2-diethoxyethane, 2-methoxyethanol,
2-methoxy-propyl acetate, ethyl acetate, butyl acetate, isopropyl laurate, methyl methacrylate, tetrahydrofuran, dioxane, acetonitrile, benzonitrile, nitrobenzene, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, N- Methylpyrrolidone, pyridine,
Picoline, quinoline, dichloromethane, chloroform,
Examples include methylcyclohexane, benzene, toluene, xylene, diisopropylnaphthalene, anisole, and chlorobenzene. Of course, these solvents can be used as a mixture of two or more kinds.

In the present invention, as a method for filling the porous fired core with a solution of the compound which is the pigment precursor represented by the general formula (I), the porous fired core is immersed in the solution. Further, if necessary, the pores are filled under conditions such as heating, pressurizing, and depressurizing. Thereafter, the organic solvent is dried and removed, and 100 ° C to 250 ° C, preferably 150 ° C to 20 ° C.
Heating at 0 ° C., particularly preferably 160 ° C. to 200 ° C. for each pigment precursor at the optimum temperature,
Is converted into an organic pigment. In some cases, it is also possible to use a catalyst such as an acid, for example, to lower the pigmentation temperature. The heating time for pigmentation varies depending on the heating temperature, the diameter and shape of the core pores, and other conditions, and cannot be unconditionally limited, but is generally from several seconds to several hours, and is preferably about 1 minute to 30 minutes. Further, in order to increase the drawing line density, immersion and heating may be repeatedly performed. In addition, the compound which is the pigment precursor represented by the general formula (I) can be mixed, dissolved in the organic solvent, and heated to be mixed into an arbitrary color. Further, as a method of filling the pigment in the core, when the porous fired core is excellent in acid resistance and alkali resistance, the organic pigment is dissolved in hot concentrated sulfuric acid or a mixed solution of sodium hydroxide and dimethylformamide. A method of impregnating the core body and then immersing it in water to return to a pigment, a method of impregnating a dye solution and then forming a lake (pigmenting) in the core body, and the like may be used in combination. Next, finally, after the compound represented by the general formula (I) is converted into a pigment, the remaining portions of the pores of the core are coated with the general formulas (II) to (IV)
A polyethylene glycol fatty acid ester of the above-mentioned general formula (I);
It is completed by filling at least one selected from the polyoxyethylene alkyl ethers of I) and the polyoxyethylene alkyl phenyl ethers of the general formula (IV).

In the compounds represented by the general formulas (II) to (IV), n needs to be n ≦ 20 or more in view of the solubility of water in the drawing, but when more solubility is required,
n ≦ 25 is desirable. Compounds having n less than 20 are not preferred because the solubility of the drawn lines in water is insufficient. As a method of filling the core, the porous fired core after the pigmentation is heated and melted in the general formulas (II) to (I).
It is immersed in the compound represented by V), and is filled into the remaining pores of the core under conditions such as pressurization and decompression as necessary. Further, by lowering the melt viscosity by mixing with a highly volatile organic solvent compatible with the compounds represented by the general formulas (II) to (IV), preferably an organic solvent having a boiling point of 150 ° C. or lower,
It is also possible to adjust the filling amount of the compounds represented by the above general formulas (II) to (IV) by promoting the permeability of the core into the pores and drying and removing the organic solvent after impregnation.
Of course, the compounds represented by the general formulas (II) to (IV) can be used as a mixture of two or more. Also, if necessary, a lubricant such as oil, an ultraviolet absorber,
It is also possible to use a light stabilizer, an antistatic agent and the like mixed with the compounds represented by the above general formulas (II) to (IV).
Furthermore, if light resistance is not required, the drawing lines are intentionally faded,
When it is desired to change the color, a part or all of the pigment obtained from the general formula (I) may be replaced with a dye.

In the water-soluble baked color pencil lead of the present invention and the method for producing the same, the following (1) and (2)
And the like. (1) Since the skeleton of the water-soluble calcined color pencil lead of the present invention is made of ceramics or clay, even if the compounds represented by the above general formulas (II) to (IV) filled therein absorb moisture, the lead itself is not used. Since water does not deteriorate and the strength is hardly reduced, a water-soluble calcined color pencil lead that can be used as a lead for a mechanical pencil or a holder is obtained. After drawing on paper, the core becomes powder on the paper, and when the drawn line is traced with a brush or the like painted with water, the compounds represented by the general formulas (II) to (IV) dissolve in water. Because the drawing lines also dissolve, the color becomes watercolor. (2) The compound represented by the general formula (I) can be dissolved in an organic solvent at a high concentration, and a sufficient amount of pigment for obtaining a high drawing concentration can be easily filled in the pores of the core. Since this horizontal pigment is stable over time, the present invention provides a water-soluble calcined color pencil lead having vivid color development, sufficient drawing line density, and excellent stability over time such as light resistance.

[0018]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. The compounds (pigment precursors) represented by the general formula (I) of the present invention used in the following Examples and Comparative Examples are shown in Table 1 below.

[Table 1]

Example 1 Boron nitride 40% by weight Vinyl chloride resin 43% by weight Dioctyl phthalate (DOP) 16% by weight Oleic amide 1% by weight The above composition was mixed and dispersed by a Henschel mixer, After kneading with this roll, it is extruded into a fine wire and heat-treated at 180 ° C for 10 hours in air to remove the residual plasticizer, and then heated to 1000 ° C in a nitrogen atmosphere. The mixture was heated and baked at 1000 ° C. for 1 hour to obtain a first baked core. The first fired core was heated and fired at 700 ° C. in the air to remove carbonized material, thereby obtaining a white second fired core. 100 g of this second calcined core was mixed with a xylene solution (20% by weight) of perhydropolysilazane.
After immersion in a container containing 40 g, 1200 g in a nitrogen atmosphere
C. and baked for 1 hour at 1200.degree.
A 57 mm white third fired core was obtained. Next, Table 1 above
Pigment Precursor No. Ethyl acetate solution of 1 (20% by weight)
The above-mentioned third fired core was immersed in the mixture and left at room temperature for 24 hours.
After standing, the core was removed from the solution,
The core was immersed in polyoxyethylene lauryl ether (n = 25) heated to 80 ° C. and left for 24 hours. Thereafter, the core was taken out and the surface of the core was wiped off to obtain a yellow fired pencil lead having a diameter of 0.57 mm.

Example 2 A third white fired core was obtained in the same manner as in Example 1 except that the diameter was changed to 0.71 mm. Next, the pigment precursor Nos. The third fired core was immersed in a toluene solution (15% by weight) of No. 2 and left at room temperature for 24 hours. After standing, the core was removed from the solution, heated at 180 ° C. for 20 minutes, and further heated to 80 ° C. with polyoxyethylene oleyl ether (n = 5).
The core was immersed in 0) and left for 24 hours. Thereafter, the core was taken out and the surface of the core was wiped off to obtain a red fired pencil lead having a diameter of 0.71 mm.

Example 3 A white third fired core was obtained in the same manner as in Example 1 except that the diameter was changed to 0.90 mm. Next, the pigment precursor Nos. The third fired core was immersed in a cyclopentanone solution (15% by weight) of No. 3 and left at room temperature for 24 hours. After standing, the core was taken out of the solution and heated at 180 ° C. for 20 minutes.
Mixed solution heated to 0 ° C. [polyoxyethylene octyl phenyl ether (n = 30): ethyl alcohol =
7: 3], and left for 24 hours. afterwards,
Take out the core and wipe the core surface, 0.90mm in diameter
Red violet fired pencil lead.

Example 4 Pigment precursor No. 1 shown in Table 1 above was used.
4 was immersed in a tetrahydrofuran solution (15% by weight) as in Example 2 and allowed to stand at room temperature for 24 hours. After leaving, the core is removed from the solution,
The core was immersed in polyethylene glycol monostearate (n = 40) heated at 80 ° C. for 20 minutes, and further left at 24 ° C. for 24 hours. Thereafter, the core was taken out and the surface of the core was wiped off to obtain a light blue fired pencil lead having a diameter of 0.71 mm.

Example 5 100 g of the second fired core similar to that of Example 1 was immersed in a vessel containing 140 g of a xylene solution of verhydropolysilazane (20 wt%), and then heated to 1200 ° C. in the air. Then, it was fired at 1200 ° C. for 1 hour to obtain a third fired core having a diameter of 0.57 mm. Next, the pigment precursor Nos. 1 in toluene solution (2
0% by weight), and left at room temperature for 24 hours. After standing, remove the core from the solution,
The core was heated at 0 ° C. for 20 minutes and further immersed in polyoxyethylene cetyl ether (n = 30) heated to 80 ° C.
It was left for 24 hours. Thereafter, the core was taken out and the surface of the core was wiped off to obtain a yellow fired pencil lead having a diameter of 0.57 mm.

Example 6 Compounding Composition A Zirconium acetylacetonate / ethyl acetoacetate 30.00% by weight Water 1.75% by weight Hydrochloric acid (36%) 0.45% by weight N-butyl alcohol 44.30% by weight The composition A was heated at 35 ° C. for 1 hour. Blended composition B 13.00% by weight of shelf nitrides 6.60% by weight of polyvinyl butyral 3.90% by weight of tetraethylene glycol 3.20% by weight of blended composition A, which has been refluxed, is added to the blended composition B, and these are mixed and dispersed by a mixer. After kneading with two rolls, adjusting the amount of solvent, extruding into a thin line, drying at 200 ° C in air to remove the remaining solvent and plasticizer, and up to 1700 ° C in an argon gas atmosphere. Raise the temperature,
It was baked at 1700 ° C. for 1 hour. In addition, 700
Temperature, and calcined at 700 ° C for 3 hours.
m was obtained. Next, the pigment precursor Nos. The third fired core was crushed in a tetrahydrofuran solution (20% by weight) of No. 3 and left at room temperature for 24 hours. After leaving, the core was taken out of the solution, heated at 180 ° C. for 20 minutes, further immersed in polyoxyethylene lauryl ether (n = 25) heated to 80 ° C., and left to stand for 24 hours. Thereafter, the core was taken out and the core surface was wiped off to obtain a red-violet fired pencil lead having a diameter of 1.0 mm.

Example 7 Boron nitride 40% by weight Kaolin 35% by weight Polyvinyl alcohol 18% by weight Polyethylene glycol 7% by weight Water and the same weight of the above composition were mixed and dispersed with a Henschel mixer, and then mixed with two rolls. After kneading and adjusting the water content,
It is extruded into a thin wire and heat-treated at 105 ° C. for 15 hours in air to remove residual water. Thereafter, the temperature is raised to 1100 ° C. in argon gas to reach 110 ° C.
It was baked at 0 ° C. for 1 hour. Further, it was heated and fired at 700 ° C. in the air to remove the carbonized material, thereby obtaining a white fired core having a diameter of 1.2 mm. Next, the pigment precursor Nos. The third fired core was immersed in a toluene solution (15% by weight) of No. 2 and left at room temperature for 24 hours. After standing, the core was removed from the solution, heated at 180 ° C. for 20 minutes, and further heated to 80 ° C. with polyoxyethylene oleyl ether (n = 5).
In 0), the core was removed and left for 24 hours. Thereafter, the core was taken out and the core surface was wiped off to obtain a red fired pencil lead having a diameter of 1.2 mm.

[Comparative Example 1] Pigment precursor N shown in Table 1 was similarly applied to the same fired core (third fired core) as in Example 1 above.
o. 1 was impregnated with an ethyl acetate solution (20% by weight) and heated. Next, polyoxyethylene lauryl ether (n =
The core was immersed in the solution changed to 2) at 80 ° C. and left for 24 hours. Thereafter, the core was taken out and the surface of the core was wiped off to obtain a yellow fired pencil lead having a diameter of 0.57 mm.

Comparative Example 2 Carboxymethylcellulose sodium salt 6% by weight Kaolin 60% by weight DPP red pigment 14% by weight Montan wax 5% by weight Polyoxyethylene oleyl ether (n = 50) 15% by weight Same weight as the above composition And water with a Henschel mixer, knead with two rolls, and adjust the water content.
Extruded into a thin wire and heat-treated at 45 ° C. for 75 hours in air to remove residual water.
mm fired pencil lead.

The baked color pencil cores of Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated for flexural strength, flexural strength after moisture absorption, and solubility of drawn lines in water by the following evaluation methods. The results are shown in Table 2 below.

[Evaluation method of bending strength]
The bending strength of the core was measured according to -S-6005. [Bending strength after moisture absorption] The bending strength after moisture absorption was 35 ° C and 80 ° C.
%, And the bending strength of the core was measured by the above method.

[Evaluation Method for Solubility of Drawing Lines in Water] A constant load (3N) was applied to the core, and the core was wetted and traced with a brush containing water. The solubility was visually evaluated according to the following evaluation criteria in five stages. Evaluation criteria: ◎: dissolves so as not to show painted marks 痕: dissolves but leaves painted marks remaining △: dissolves about half △△: slightly dissolves X: does not dissolve or hardly dissolves

[0031]

[Table 2]

As is clear from the results shown in Table 2, in Examples 1 to 7, which are within the scope of the present invention, it is found that the drawn lines have good solubility in water, high bending strength, and are stable even when absorbed. did. On the other hand, Comparative Example 1 hardly dissolves the drawn line because n of polyethylene glycol lauryl ether is small, and Comparative Example 2 is a non-fired core, has low strength, and the blended polyethylene glycol oleyl ether has Since it easily absorbs moisture, it is not usable for mechanical pencils and holders when left in the air because of its reduced strength.

[0033]

According to the present invention, the drawing line is easily dissolved in water to obtain a watercolor-like drawing, and at the same time, vivid color development,
A water-soluble calcined colored pencil lead having sufficient drawing line density, capable of writing a drawing line having excellent light resistance and weather resistance, and having excellent mechanical strength such as bending strength, and a method for producing the same are provided.

Claims (4)

[Claims] 1. A pigment starting from at least a compound represented by the following general formula (I) in pores of a white or light-colored porous fired core, and a pigment represented by the following general formulas (II) to (IV): A water-soluble calcined colored pencil lead comprising at least one compound selected from the group consisting of: Embedded image Embedded image 2. The white or light-colored porous sintered core comprises a colorless or white body material and silicon nitride starting from perhydropolysilazane as a binder. Water-soluble baked colored pencil lead. 3. A white or light-colored porous fired core is formed, and at least the following formula (I) is formed in pores of the fired core.
After dissolving the compound represented by in an organic solvent and filling,
It is characterized in that the compound is heated to form a pigment in the pores, and the remaining portion of the pores is filled with at least one of the compounds represented by the following general formulas (II) to (IV). A method for producing a water-soluble calcined colored pencil lead. Embedded image Embedded image 4. A white or light-colored porous fired core body comprising a colorless or white body material and silicon nitride starting from perhydropolysilazane as a binder. A method for producing a water-soluble calcined colored pencil lead.